Steam-accumulator apparatus for steam plants



- J. K. Ru rHs STEAM ACCUMULATOR APPARATUS FOR PLANTS File d Nov- 7.191919 3 Sheets-Sheet 1 July 1 -1924. 1,499,697

.KjRuTHs STEAM ACCUMULA'I'OR APPARATUS FOR STEAM PLANTS Fild Nov. 1. 1919 a Shets-Sheet 2 July 1 19.

J.K. RUTHS STEAM AQCUMULATOR APPARATUS FOR STEAM PLANTS Filed Nov; 1.. 1919 3 Sheets-Sheet 5 V W .Z w a. B w v 5 w w f & g M w a 2 Id ranged in a conduit Patented July 1, 1924.

I p Y 1,499, 97" UNITED STATES r TEN oFr-"lca.

'zrommnns KARL Burns,

- varoaacxomomron', or

CE DJ'UBSHOLM, SWEDEN,

STOCKHOLM, SWEDEN, A CORPORATION.

ASSIGNOB '10 AKTIEBOLAGET STEAH- -ACQUMULATOR APPARATUS FOR STEAM PLANTS.

Application filed November 1, 1919. Serial No. 335,118.

To all whom it may concern:

Be it known that I Roms, subject of the siding at Djursholm, in the Kingdom of Sweden, have invented certain new and useful Improvements in Steam-Accumulator Apparatus for Steam Plants, of which the following is a specification.

In steam plants provided with steam accumulators, a valve mechanism has been arsupplying steam from the generator to the accumulator and it operated, when the pressure in the conduit increased above a predetermined value to increase the steam supply through the conduit, and it acted to throttle the steam supply upon a decrease of the pressure below a predetermined value, the object of such an arrangement being cally constant pressure in the steam generator and in the connected conduit system in order to bring about an independence between the momentary steam consumption. In the operation of such plants however the drop in pressure J OHANNES KARL due to the throttling down of the steam took place at the valve mechanism itself and no power was extracted in this pressure drop. By causing this drop of pressure to take place within a steam motor certain advantages are gained, and power may be extracted from the steam before it is lead to the accumulator. In a copending application filed by me of even date herewith, Serial No. 335,112, I have described and claimed a steam accumulator plant wherein it is possible to obtain power from the steam availconsumption,

able, even on great variations in the steam or steam supply, or both, and wherein the pressure in the boiler is mainso thatthe boilers may operate at the highest efliciency, and

this was efiected by arranging a steammotor to receive steam from the generator and to supply steam to the accumulator, and a valve mechanism to control the flow of steam to the motor and governed in its action by the pressure of steam. in front of the valve mechanism.

The present invention aims to efl'ect'this same general result, and the invention consists of an improved arrangement of parts, which will be fully described hereinafter in detail, whereby the invention is more particularly adaptab-l'ein its'application to the King of Sweden, re-

nected with conduit to maintain a -practisteam generation and type of steam motors now universally employed. 1

In my present invention, a steam. motor is employed comprising a plurality of units including a high pressure unit and a lowpressure unit,'the high pressure unit being supplied with steam, from a conduit conthe generator, and the low pressure unit receiving steam from the igh pressure unit directly or through an intermediate pressure unit, a steam accumulator being supplied with steam from the motor, and a valve mechanism being inserted in the connection leading steamto the low pres- I sure unit and actuated by the pressure in the from which the high pressure unit is supplied in order to control thesteanr suppliedto the low pressure unit, and a regulating means is providedto control the steam supplied to the high pressure unit. The form of these parts is such that if the pressure in the conduit pressure unit is supplied, should increase, the valve mechanism will throttle the steam supply to the low pressure unit, whereby the said regulating means will act to admit more steam from said conduit to the high from which the high pressure'unit, and more steam will flow to the accumulator; and if on the other hand the pressure in the said conduit decreases, steam supply to the lowpressure unit W1 be increased, thereby causing the re ulat' means to decrease the steam supply rom conduit to the high-pressure unit.

Thus when the pressure in the conduit from which the high pressure unit is supplied increases due to a momentary surplus of steam generated over the momentary consumption, this surplus of steam generated is led through the hi h pressure unit to the accumulator and at t the g to V esame time, to facilitate this object, the load on the low pressure unit is, in part or in whole,transferred to the other unit orunits.

The invention consists also in the details of construction and combination of parts; hereinafter described and claimed.

The invention will be described more in detail in reference to the examplesshown in the accompanyirg drawings, In which: Fig. 1 is a view of a steam plant having my invention embodied therein with a steam motor of the single extraction type. Fig. 2 is a view of a plant similar to that shown in Fig. 1, but with a difierent relative arrangement of the steam coners.

Fig. 3 is a view similar to Fig. 2, but with a steam motor of the double extractiontyp'e.

Fig. 4 is a, sectional view of the valve mechanism for controlling the steam supply to the low pressure unit of the motor.

' ig. 5 is a sectional view of two mechanically interconnected valves controlled by the pressure in motor.

Fig. 6 is a sectional view of two mechanically interconnected valves controlled by a single speed governor.

Referring to the drawings:

Referring to Fig. 1 a steam motor, in this case a turbine is shown comprising a high pressure unit H and a low pressure unit L. The high pressure unit receives steam from a steam generator P through a conduit 1L, and a branch conduit L, and steam is supplied to the low pressure unit from the high pressure unit by means of a conduit L connecting the two units, in which conduit there is inserted, in accordance with my invention, a valve mechanism V This valve mechanism is operated by the pressure in the conduit 1 acting through a conduit L the valve mechanism being of a form and construction, asflwill be more fully described later on, which will increase the supply of steam to the low pressure unit upon a decrease of the pressure in the conduit 1L below a predetermined value, and which will throttle the steam supply to the low pressure unit upon an increase of pressure in the said conduit above a predetermined value.

. A steam accumulator A is arranged to ref ceive steam from the motor, in the present instance through a conduit L leading from the conduit L, at a point in front of the valve V and connecting with a conduit L to which the accumulator is connected in parallel, suitable non-return valves lB-B being inserted in the connections between the accumulator and the conduit L and the direction of steam flow through the non-return valves being indicated by the arrows.

The supply of steam to the high pressure unit through .the conduit L, is controlled by regulating means, in the present instance in the form of a valve mechanism V operated by a centrifugal governor C driven from the turbine, the form of the valve and its connection with the governor C as shown, being such that if the speed of rotation of the turbine increases above normal, the

valve will throttle the steam supply to the high pressure unit; and if the speed of the motor falls below normal, the valve will be moved and the supply of steam will be increased.

A valve V is inserted in the conduit L the conduit supplying the.

access? in the present instance between valve V, and the low pressure unit, and this valve is operated by a centrifugal governor C theform of the valve and its connection with the governor being such as shown, that at the normal speed of rotation of the tur- .bine. thevalve V will be held fully open with the governor balls in the position shown, and will only come into operation to close valve V, at a speed higher than that at which governor C closes valve V. Thus it will be seen that the governor C operates only in exceptional cases when governor C has closed valve V, and the speed of the motor is even then too high due to supply of steam from the accumulator through line L to the .low pressure unit.

A condenser Y is connected to the low pressure unit; and the turbine is shown as driving an electric generator G.

To the conduit L a conduit L is connected by means of a reducing valve R adapted to control the steam supply to the conduit L to maintain a practically constant pressure therein; and the steam consumcr, -for example a paper making machine M, is connected to the said conduit.

Conduit L is connected with conduit L, by means of a connecting conduit L and a valve mechanism 0 whichll term an overflow valve, is inserted therein, the function of which is to admit steam from the conduit L to the accumulator, only when in exceptional cases, the pressure of steam in conduit L, exceeds a predetermined value, at which pressure,.valve V will be completely closed. The two valves 0,, and V, may be mechanically interconnected as shown for example in Fig. 5, in order that they will operate in the proper relations to each other, as will be presently described.

, A reducing valve R is arranged in the system in parallel with the said valve 0 to admit steam to the conduit L, in case the accumulator should become fully discharged Which may infrequently occur.

A steam consumer S, which may be in the form of a paper pulp digester, is shown as connected with the conduit L but such consumer may be omitted, as it is not essential to the operation of the plant in realizing all of the advantages of the present invention.

In the operation of the plant with the parts arranged as described, wherein a steam 1 motor is arranged in the system between the generator and the steam accumulator, andwherein the accumulator receives steam under normal conditions of operation, from the motor, the accumulator will take care of all variations in the plant. Assuming for instance, that the pressure in conduit L, in creases above a predetermined value, due to decreasing steam consumption in the consumer S, or to increase of steam generation be obtained from the steam,

the steam motor,

. insane? in the generator the steam supply to the low pressure unit of the motor and consequently the rate of speed of the motor will fall below normal, and the governor C will act on the valve V and increase the steam supply to the high pressure unit. It is therefore seen that at ah increase of pressure in conduit L,, the surplus steam will be led through the high pressure unit to conduit L, by which power will while the low pressure unit will be unloaded in a corresponding degree. From the conduit L., the steam can flow either to conduit L through the reducing valve R or to the accumulator A, or to both, depending upon the pressure conditions. 1

If on the other hand the ressure in conduit L should decrease be ow a predetermined value, due to increased steam consumption, or to decreased steam generation, valve V, will be operated to increase the steam supply to the low pressure unit, and consequently the speed of rotation of the motor will be increased above normal, and the governor C will act on valve V'andwill decrease the steam supply to the high pressure unit. If in-these circumstances, ll'lSllf ficient steam is being supplied from the hijglh a pressure unit to the low pressure unit, t

deficiency can be met by steam from the ac-' which deficiency under the condi-. tions described, will be supplied from the accumulator through conduits L L and L,, whence it will pass to the low pressure unit.-

Assuming now that the demand for'power is increased beyond that being furnished by then the speed of the rotation of the motor will fall, and the governor C will act to admit "more pressure unit. As a result, -the pressure in conduit L will decrease and consequently cumulator,

- valve .V .w1ll be actuated to admit more [steam to the low pressureunit, which steam may be,taken from the high ressure vunit only, or partly from which the igh pressure unitand partlyfrom the accumulator according to the conditions. The speed of rotation of the motor will therefore increase, and the governor steam supply to the high pressure unit. If, in these c rcumstances, insuflicient steam is being supplied from the to the low pressure unit, the de ciency, a'sin the previous case where it was assumed that pressure in conduit L decreased, can be met y steam from the accumulator, so that where ener demand is reater than what is supfrom conduit L to the motor as a whole, .the accumulator supplies the deficiency. r i Fromthe foregoing description it will be understood that the steam supplied by the accumulator to the low pressure "unit had, previous to its p to the low pressure P, the valve V will throttle steam to the high C will act to throttle the:

high ressure: unit way of example,

unit, passed through the high pressure unit on its way to the accumulator, and power had therefore been obtained therefrom.

I Again it will be understood that if the demand for power should decrease, the s eed of rotation of the motor will increase a ove the normal, and the steam supply to the high pressure unit will be throttled, and

ressure in conduit L increasing valve V will be operated to decreasethe steam supply to the low pressure unit. Consequently the speed of rotation will decrease, and more steam will be led to the high pressure unit and thence to the accumulator. In this action therefore the low pressure unit will be unloaded corresponding to the degree of decreased demand for power.

If the speed of rotation should increase to such a degree that the steam supply to the high pressureunit is fully shut oil, then on further increase of speed of the motor, governor C, will come into action and will operate valve V and will throttle the steam supply to the low pressure unit coming from y the several parts, pressure in conduit it will be seen that the L will be maintained at a practically constant value, notwithstand-' ing the varying conditions that may. take place.' i

.' -.The devices shown in. Fig. 1 take care of all variations in the system, which variations may be caused by an increase or a decrease in the steam consumption, or by irregularities in the fuel supply. These latter variations are, for instance, caused b sla'gging, or they may arise in the feeding of the boiler. In fact, measurements taken at a plant runningunder entirely normal condithat very great variations tions have shown even 1n cases where the may occur. But

fuel is, available in variable quantities, as,

for instance, in the case of blast furnace gases, waste heat from furnaces, or other sources 0, serve to inaintain the boiler pressure at a fully constant value. The variations may occur in the power consumption of generator G. The same .result will be obtained if the consumption of consumers S and M, or both, equal zero.

.Fig. 4 shows a form of the valve V by suitable for the realization of my inventlon. Here it will be seen that a valve casing-2 is' formed with op sitely disposed ports 3 and 4 adapted to b nected in. the conduit L the port 3 being connected with. a chamber These ports 6 and 7 are controlled by a balanced valve-member 8 movable with a valve stem 9 guided in the casing, and having connected with it a piston F sliding in a cylinder 10. The piston is acted on at one side f variable heat supply, the devices 5 extending into .the casing and having aligned ports 6 and 7.

, by a spring ll arranged within the cylinder,

and on the other side by the pressure of steam in conduit L acting through the con-' duit L which is connected to. the end of the cylinder. The arrangement is such that the pressure of steam in the cylinder tends to L and on the decrease of the pressure in the cylinder to a degree below the force of the spring, the latter will move the piston and will open the'valve and permit a freer passage of the steam.

Fig. 2 shows a steam plant of substantially the same construction as that shown in Fig. 1. In Fig. 2 however the steam from the motor is led to a conduit L supplying a consumer B the said-conduit L connecting with conduit L by meansof an over-flow valve 0 and the conduit L being connected with the accumulator as before. Also in this case the additional conduit L is connected to the conduit L, by means of-a reducing valve R the over-flow'valve 0 of Fig. 2 corresponding to the over-flow. valve 0 of Fig. 1. The operation of the parts as shown in this figure is, so far as the principle of fny inventionis concerned, substantially the same as the operation of the parts Fig. 1.

Fig. 3 shows a plant substantially similar to that shown in Fig. 2, the main .difi'erence being that in Fig. 3 the turbine is of the double extraction type, comprising a high pressure unit H, an intermediate pressure,

nnit M and a low pressure unit L, the controlling valve V being inserted in the connection between the intermediate pressure,

unit and the low pressure unit, the conduit L receiving steam from the intermediate pressure unit, and the conduit L receiving steam from the high pressure unit. These two conduits are connected together by means of a branch conduit containing an over-flow valve 0 and a second-branch conduit connects said conduits and contains "a reducing valve R the said conduits L and L supplying steam respectively to consumers M and B In the connection between the high' pressure unit and the intermediate pressure unit, an overflow -valve 0 and a speed regulated valve V, are in- 'serted. In this Fig. 3 speed governors C,

C, and C are provided in connection with the respective pressure units, which governors operate in the same relations to each other as the two governors of Fig. 2. The general operation of the plant in so' far as the principle of my invention is concerned, is" substantially the same as that described in connection with Fig. 1.

31 surrounding the stem and tendin neeaeev interconnection of the over-flow valve U and the valvelV' as hereinbefore referred to. Here it will be seen that a valve member '12 corresponding to valve 0 of Fig. l,

'18 extendsinto the casing 14. from port 17 and is provided with aligned ports 19 and 20 which are controlled by the valve member 12. Casing 15 is formed with two ports 21 and 22, the port 21'. receiving steam from the high pressure unit of the motor, and the port 22 supplying steam to the low pressure unit. Port 22 has connected with it a chamber 23' extending into the casing and provided with ports 24' and 25 controlled by the valve member/13. The two valve members 12 and,13 are. mounted loosely on a common valve actuating stem 26 guided in the casing structure and connected at one end to a dpiston 27 sliding in a cylinder 28, the sai cylinder at one side of the piston being in communication with the interior of. the valve casing 14:, and the piston on its opposite side being acted on by a spring 29 exertin its force in opposition to the pressure 0 the steam. Valve member 12 is e'nga ed by a collar 30 100 on the. stem and is acte on by a sprung 0 hold the valve member in closed posi ion. Valve member 13 is enga ed, by a collar 32 on the stem and is acte on by a sprmg 105 33 sustained by the stem and tending to hold thevalve member closed.

In the operation of this mechanism, 1f the pressure in conduit L, acting 1n casing 1 1,

should fall below a predetermined value,

spri'n 29 will move the piston and connecte valve stem, and collar 32 thereon engaging the valve member 13 w1ll open the same and steam from the hlgh pressure unit will flow to the low pressureumt through ports 21 and, 22. In this posit on of the parts, valve member 12 corresponding to the over-flow valve 0 of Fig. 1, for mstance, will remain closed, due to the action of its spring 31. llfnow pressure in con duit 1L acting in valve casing 14:. should increase, piston 27 will be moved 1n the opposite dlrection and Wlll move valve. stem 26, and valve member 13 will act to throttle 'the'steam supply to the low pressure unit,

' by mcansot collar 30- 5 Fig. 5 shows the details of the mechani I is seen therefore that when valve memwhich cylinders pressure fluid this arrangement permitting access? ber 13 is closed and shuts oif steam to the low pressure unit, a further increase of the pressure in conduit L will open valve member 12 and steam will be led from conduit L, to the accumulator.

Wh1le'in each of Figs. 1, 2 and 3 aplurality of speed governors isv shown for the turbine, with each overnor connected to operate its associated valve member, it will be understood that a single speed governor may be employed and connected to actuate a plurality of valve mechanisms, so that the valves will be operated in succession as the speed of the motor increases. Such a mechanism is shown'in Fig. 6 with one speed governor operating two valve mechanisms. In this figure it will be seen that the two valve mechanisms V and V have their valve stems S and S connected respectively with piston plungers 21 and sliding in power cylinders, to is admitted by pipes 25 and 24, and from which the pressure fluid exhausts by pipes 28 and 29,

26 and 27 the control of the and from the cylinders being efiected by slide valves 23 and 22 connected to levers 17 and 16, which levers are in turn connected to the valve. stems S, and S The lever 17 is acted on by springs 19 which hold it position, and the end of the lever is formed with an opening through which loosely slides a rod 15 provided with spaced collars 18 disposed on opposite sides of the lever 17 of a limited the rod relative to the;

and pipes pressure fluid to movement or play of lever without afiecting the latter. The rod is connected to the lever 16 and to a lever 14-. fulcrumed at one end, and a centrlfugal governor C---'C is operatively connecte with lever 14 to rock-the same more or less V, will 1 of slide 23 controlling I scribed,

according to the s eed of revolution.

The relation an form of the above de-' scribed parts are such that under the normal number of revolutions of the governor both valves will be held in open position as shown. hould the number of revolutions increase, valve V will start to close, in whichaction rod 15 will move, due. to its play relative to the lever 17, without movmg the latter, and consequently valve remain open. If now the number of revolutions further increases, valve will be completely closed, and in collar 18 will act on'lever 17,v and by means the piston 21, valve V will be throttled. The two valves V and V correspond in this example to the valves V and V of Fig. 1.

From the operation of the parts ust."deit will beseen that at the normal speed of the motor, the steam suppl to the .high ressure umt will be contro led by 1 valve V, while on further increase of speed closure of valve V, valve yieldingly in a neutral conduit above a the steam supply tothe motor,

this action above normal, and resultin in the complete steam supply to the low pressure umt, begin to close and will thus throttle the steam supply to this unit. i

There is shown in connection with Figs. .1 to 3 a pressure gage M, connected with the steam accumulator b .means of a pipe L the operation of w ich ga e is fully set forth in my application {serial No. 305,622; and as this pressure. gage is not directly concerned with the resent invention it will-not be necessary or a complete understanding of the invention to describe the same more fully herein.

Having thus described my invention, what I claim 1s:

.tion a steam generator, a steam conduit connected thereto, a steam motor connected to said conduit, said'motor comprising a pluralit of units including a low pressure unit, regu ating means to control the steam supply to the motor fromsaidconduit, means actuated by the pressure in the conduit from which the motor is supplied, and operating to control the supply of steam to the low pressure unit and a steam accumulator connected to the motor ahead of said last means.

, 2. Asteam plant comprising in combination a steam generator, a steam conduit connected therewith, a steam motor comprising a high pressure unit connected with the COD".

duit, and alow pressure unit receiving steam from the high pressure mulator receiving steam from the high pressure unit, means actuated by the pressure in the conduit from which the high pressure unit is supplied and operating to throttle the steam supply to the low pressure unit upon an increase'of pressure in the supply predetermined value, and means for increasing the supply of steam to the high pressure unit when the supply to the low pressure unit is throttled.

3. A steam plant comprising in combination a steam generator, a steam conduit connected thereto, a steam motor connected to said conduit, said motor comprising aplurality of units including a low pressure unit, speed regulated means adapted .to control a valve member adapted to control the steam supply to the low i ressure unit, and means for actuating said valve member to increase the steam supply to the low pressure unit upon a decrease; of the pressure below a predetermined value in the said conduit from which the motor is supplied, while throttl ng the steam supply upon an increase of said pressure above a predetermined value, and a steam accumulator receiving steam from the motor ahead of said valve member.

,1. A- steam plant comprising. in combinaunit, a steam accu- 2 controlling the tion a steam generator, a steam conduit connected thereto, a steam motor comprising a high pressure unit connected to said conduit and a low pressureunit, a connection receiving steam from the high pressure unit and passing steam to the low pressure unit, speed regulated means adapted to control the steamsupply to the high pressure unit, a' valve member adapted to control the steam supply to the low pressure unit, means for actuating said valve member to increase the steam'supply to the low pressure unit u on a decrease of the pressure below a pre etermined value in the said conduit from which the high pressure unit is supplied, while throttling the steam supply upon an increase of said pressure above a predetermined value, a steam accumulator,

.a connection between said accumulator and the connection passing steam to said low pressure unit, and a second speed regulated means arranged in the connection passing duit and .a low pressure unit, a conduit receiving steam from the high pressure unit and connected to the low pressure unit to supply steam thereto, regulating means to control the steam supply to the high pres- 7 sure unit, controlling means actuated by the pressure in the conduit from which the high pressure is supplied and operatingto control the supply of steam to the low'pressure unit, and a steam accumulator communicat- I mg with the second mentioned condult at a point in front ofsaid controlling means. v

6. A steam plant comprising in combination a steam generator, a steam conduit connected thereto, a steam motorcomprisin a high pressure unit connected to said cond uit and a low pressure unit receiving steam from the high pressure unit, regulating means to control the steam supply to the high pressure unit, a steam accumulator re- "ceiving steam from the high pressure unit,

and means actuated by the pressure in the conduit from which the high pressure unit is supplied, and operating to control the sup-- ply ofsteam to the low pressure unit. 7. A steam plant comprising in combination a steam generator, a steam conduit connected thereto, a steam motor comprising a high pressure unit connected to said conduit and a low pressure unit receiving steam from the high pressure unit, regulating means to control the steam supply to the high pressure unit, a steam accumulator receiving steam from the-motor, means actu= neeaeev ated by thespressure'in' thefcon'duit from which the high pressure unitis supplied and operating to 'control the supply of steam to the low pressure unit and a 'steam'consumer supplied with steam from the hign pressure unit. 0-

8. A steam plant comprising in combination a steam generator, a steam conduit connected thereto, a steam motor comprising a high pressure unit connected to said conduit, an intermediate pressure unit receiving steam from the high pressure unit, and a low pressure unit receiving steam from the intermediate pressure unit, regulating means to control the steam supply tothe high pressure unit, means actuated by tlfe pressure in the conduit from which the high pressure unit is suppliedand operating to control the supply of steam to the low pressure unit, a conduit supplied with steam from the high pressure unit, a steam consumer connected therewith, a conduit receiving steam from the intermediate pressure unit, a steam consumer connected thereto, and a steam accumulator connected to the last mentioned conduit.

9. A steam plant comprising in combination a steam generator, a steam conduit connected thereto, a steam motor comprising a high pressure unit connectedto said conduit, and a low pressure unit receiving steam from the high pressure unit, regulating means to control the steam supply to the high pressure unit, a steam accumulator receiving steam from the high pressure unit, means actuated by the pressure in the conduit from which the high pressure unit is supplied and operating to control the supply of steam to the low pressure unit, and to cut 0% said supply when the pressure in the steam conduit increases above a predetermined value) a branch conduit connecting the said conduit from which the motor is supplied, with the accumulator, and a valve mechanism in said branch conduit adapted to open and admit steam in direction toward the accumulator upon an increase of pressure in the first conduit above the value suficient to shut 0d the steam supply to the low pressure unit.

10. A steam plant comprising in comhp nation a steam generator, asteam condult Lil.)

connected thereto, a steam motor comprising a high pressure unit connected to said'conduit and a low pressure unit receiving steam from the high pressure unit, speed regulated means adapted to control the. steam supply to the'high pressure unit, a steam accumulai tor receiving steam from the high pressure determined value in the said conduit, w ile ace v throttling the steam supply upon an increase of said, pressure above a predetermined value, a branch conduit connecting the first mentioned conduit with the accumulator,

and a valve mechanism in said branch conduit adapted to open and admit steam in d1- 7 rection toward the accumulator u on an innected thereto, a steam motor comprising a high pressure unit connectedto said conduit and a low ressure funit receiving steam from the high pressure unit, regulating means to con trol the steam suppl to the high pressure unit, a steam aceumu ator receiving steam from the high-pressure unit,

means actuated by the ressure in the eon- 20 duit from which the high pressure unit is suppliedand operating to control the supply I of steam to the low pressure unit, and a steam consumer supplied with steam direct from the said conduit. I

In testimony whereof I aflix my'signature in presence of two witnesses.

JOHANNES KARL RUTHS.

Witnesses:

Lu'rz E. HALLIN, P. H. Bnneno'rn; 

